I. Field of the Invention
The present invention relates to wheelbarrows. More particularly, it is directed toward a wheelbarrow with a manually actuated braking system.
II. Description of the Related Art
Wheelbarrows are commonly used to transport such materials as earth, sand, and cement. Such wheelbarrows are usually manually propelled. An operator must apply propulsive force to the frame of the wheelbarrow to set it in motion. To stop the wheelbarrow, he must apply a retrograde force to overcome the momentum of the wheelbarrow. Because a loaded wheelbarrow can have significant mass, it can acquire a considerable amount of momentum and can be difficult to stop. This task is even more difficult when the operator is guiding the wheelbarrow down an inclined plane, because the force of gravity tends to accelerate the wheelbarrow down the ramp. In such a situation, it is possible that the operator will be unable to exert sufficient retrograde force to brake the wheelbarrow. He could then lose control of the wheelbarrow. This is an extremely dangerous situation and can result in personal injury or property damage.
To enable an operator to stop a wheelbarrow or to prevent it from accelerating out of control, operator-actuated braking systems have been added to wheelbarrows. However, previously disclosed wheelbarrow braking systems have suffered from a significant disadvantage--the braking force is generated by frictional contact between a brake member such as a shoe and an exposed portion of the wheelbarrow's wheel or tire. Since wheelbarrows are most often used out of doors, water, mud, or oil can be splashed or carried up onto the outer surfaces of the wheel. If this happens, the effective coefficient of friction between the brake member and the tire or wheel will be significantly reduced, as will the braking force which can be generated.
This problem is inherent in the braking systems disclosed in U.S. Pat. Nos. 2,716,031 to Roessler and 3,950,005 to Patterson. The Roessler patent discloses a hand-operated brake for a wheelbarrow in which the braking force is generated by frictional contact between a brake shoe and the exposed, cylindrical rim of a wheel to which a tire is attached. The Patterson patent discloses a brake apparatus for a manually propelled, material-handling vehicle. The brake apparatus disclosed by Patterson develops braking force through the frictional engagement of a brake shoe with the periphery of a wheel or tire. An inspection of these patents readily reveals how the effectiveness of the braking systems they disclose will be quickly degraded in typical operating environments. It is very easy for foreign matter to become interposed between the brake member and the wheel and thus interfere with the generation of the required braking force.